This invention relates generally to the handling of spent nuclear materials and more particularly to the handling of spent nuclear fuel rods for transportation to storage areas or for further treatment.
The generation of power from nuclear materials has been well known in the art for many decades whether the generation is for naval vessels or for electric utility power for commercial use. The nuclear material has after a period of time been unable to generate the energy necessary and must be removed from the reactor and stored temporarily in the conventional wet pit, which is an enclosed environment where the nuclear material, usually in the form of rods, is immersed in water. The purpose of the water is to allow the rods to cool from the very high radioactivity that would be experienced in the reactor. Wet pits have been used for many years to store the spent nuclear fuel rods but in recent times the storage capability of the wet pits has become limited and it is necessary to remove the spent nuclear fuel rods from the wet pit and transport them to a temporary storage site or to permanent storage as in a deep hole in the earth or within a mountain or the like, or have the rods reprocessed.
The transportation of such a spent nuclear fuel rod has been a troubling problem over the decades and one that has not been solved satisfactorily. The problem has become more acute in very recent times and must be solved successfully if nuclear energy is to thrive as an energy source.
The current commercial industrial practice is not a dry fuel rod transfer but rather includes the step of submerging a storage cask into the nuclear fuel storage wet pit that is typically maintained by electric utilities. Then under water through the use of cranes and grappling hooks and the like, the spent nuclear fuel rods are transferred while still under water into the submerged storage cask. The storage cask is then lifted from the wet pit, the interior drained and the cask dried on the outside and sealed. Many utilities cannot use this process to transfer spent nuclear fuel because of constraints on existing utility lifting and handling resources.
As the water in the wet pit is contaminated with nuclear materials so would the exterior of the storage cask be contaminated and thus upon its emergence from the wet pit it must have its exterior decontaminated before the container can be transferred to storage.
Without the present invention, dry transfer of the spent nuclear rods would involve the construction of a large highly shielded building in which the casks are opened and the fuel moved while unshielded from one cask to another for transportation. This usually would have to be done by remotely controlled means. Dry transfer of the spent nuclear fuel rods from a wet pit to a container has been previously accomplished but in such cases the dry transfer would then be made to a container filled with water which is to be removed before transport. Removal of water from such containers requires the handling, storage and/or treatment of this radioactive material contaminated water which is highly undesirable.